{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "extension-springs",
 "name": "Extension springs, wire Ø0.6 and Ø1.0",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Motion",
 "year": null,
 "question": "What are the dimensions of a small extension spring with loop ends?",
 "tags": [
  "extension spring",
  "tension spring",
  "spring",
  "loop",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "extension spring dimensions",
  "tension spring 10mm",
  "extension spring step",
  "spring with loops"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 2,
 "url": "https://xemstudio.com/objects/extension-springs/",
 "sheet_txt": "https://xemstudio.com/objects/extension-springs/sheet.txt",
 "sheet": {
  "basis": "Close-wound helical extension spring with a loop at each end; length over the loops",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Close-wound bodies (coils at 1.02 × wire pitch so the turns stay separate) with a full loop each end; the length is over the two loops.",
   "0.6 wire × OD 6 (ID 4.8), 30 over the loops, 20 coils; 1.0 wire × OD 10 (ID 8), 50 over the loops, 25 coils.",
   "Rate follows the same k = G d⁴ / (8 D³ n) as a compression spring, plus an initial tension from close winding; the loop ID is OD − 2 × wire and takes a hook pin."
  ],
  "table": {
   "columns": [
    "file",
    "wire Ø",
    "OD",
    "ID",
    "length over loops",
    "coils",
    "index D/d"
   ],
   "rows": [
    [
     "extension-d0.6-od6-l30",
     0.6,
     6,
     4.8,
     30,
     20,
     9
    ],
    [
     "extension-d1-od10-l50",
     1,
     10,
     8,
     50,
     25,
     9
    ]
   ]
  }
 },
 "sheet_text": "Extension springs, wire Ø0.6 and Ø1.0 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/extension-springs/  (CC BY 4.0)\nBasis: Close-wound helical extension spring with a loop at each end; length over the loops\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Close-wound bodies (coils at 1.02 × wire pitch so the turns stay separate) with a full loop each end; the length is over the two loops.\n- 0.6 wire × OD 6 (ID 4.8), 30 over the loops, 20 coils; 1.0 wire × OD 10 (ID 8), 50 over the loops, 25 coils.\n- Rate follows the same k = G d⁴ / (8 D³ n) as a compression spring, plus an initial tension from close winding; the loop ID is OD − 2 × wire and takes a hook pin.\n\nfile  wire Ø  OD  ID  length over loops  coils  index D/d\nextension-d0.6-od6-l30  0.6  6  4.8  30  20  9.0\nextension-d1-od10-l50  1.0  10  8.0  50  25  9.0\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Spring (device) — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Spring_(device)\n- McMaster-Carr: Compression springs (free STEP per part, for your own design use; no redistribution) — STEP, PDF — McMaster-Carr site terms [verify license at link] — https://www.mcmaster.com/products/compression-springs/\n- Lee Spring: Spring design formulas — web — Lee Spring site [verify license at link] — https://www.leespring.com/learn-about-springs\n- Long Earth Society: Engine and rig builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 2 parts): https://xemstudio.com/files/hardware/extension-springs/index.json\nAPI: https://xemstudio.com/api/geometry?object=extension-springs\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Spring (device)",
   "url": "https://en.wikipedia.org/wiki/Spring_(device)",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "McMaster-Carr",
   "title": "Compression springs (free STEP per part, for your own design use; no redistribution)",
   "url": "https://www.mcmaster.com/products/compression-springs/",
   "formats": [
    "STEP",
    "PDF"
   ],
   "license": "McMaster-Carr site terms",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Lee Spring",
   "title": "Spring design formulas",
   "url": "https://www.leespring.com/learn-about-springs",
   "formats": [
    "web"
   ],
   "license": "Lee Spring site",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine and rig builds",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "compression-springs",
  "torsion-spring",
  "gt2-pulleys"
 ],
 "fits": [
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "gt2-pulleys",
     "why": "belt tensioner arm"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "compression-springs",
     "why": "pushes instead of pulls"
    }
   ]
  }
 ],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [
  {
   "feature": "spring OD",
   "exact": "OD (6–16)",
   "mates": "pocket of the same Ø",
   "fit": "socket",
   "files": "all"
  },
  {
   "feature": "spring ID",
   "exact": "OD − 2 × wire",
   "mates": "guide rod or arbor of the same Ø",
   "fit": "socket",
   "files": "all"
  },
  {
   "feature": "loop ID",
   "exact": "OD − 2 × wire",
   "mates": "hook pin",
   "fit": "designed",
   "files": "extension-"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "How is an extension spring's length measured?",
   "a": "Over the two loops: 30 and 50 mm on these files."
  },
  {
   "q": "What is the loop size?",
   "a": "The loop ID is the coil ID: 4.8 on the 0.6 × 6, 8.0 on the 1.0 × 10."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "extension-d0.6-od6-l30",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/springs/extension-d0.6-od6-l30.step",
   "stl": "https://xemstudio.com/files/hardware/springs/extension-d0.6-od6-l30.stl",
   "note": "extension spring envelope: wire Ø0.6, OD 6, ID 4.8, 30 mm over the loops, 20 coils"
  },
  {
   "file": "extension-d1-od10-l50",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/springs/extension-d1-od10-l50.step",
   "stl": "https://xemstudio.com/files/hardware/springs/extension-d1-od10-l50.stl",
   "note": "extension spring envelope: wire Ø1.0, OD 10, ID 8, 50 mm over the loops, 25 coils"
  }
 ],
 "markdown": "https://xemstudio.com/objects/extension-springs/index.md"
}